Used paper in an office such as classified papers is currently subjected to a finely cutting treatment. As a certain level of strength needs to be maintained during the production of recycle paper from waste paper, its recycling number has to be limited and all of the waste paper recovered is not suitable for recycling.
In the past, cellulose-containing waste such as the finely-cut office paper and a kind of waste paper that is not suitable for recycling have been mostly incinerated and not been therefore effectively utilized. Incineration leads to energy loss, and will produce a huge amount of greenhouse gas, carbon dioxide. There is a necessity of a method for utilizing the waste paper that is hard to recycle.
Recently, techniques have been reported for the production of ethanol with fermentation of glycosylated products of the cellulose-containing waste by an enzyme such as cellulase (Patent Documents 1 and 2), or an acid (Patent Document 3).